Stabilization of lubricants

ABSTRACT

STABILIZING LUBRICANTS AGAINST DETERIORATION DURING TRANSPORTATION, STORAGE AND/OR USE BY INCORPORATING THEREIN A 2-HYDROCARBYL-1,3-DI-SEC-ALKYL OR DI-CYCLOALKYL-2H-1,3,2BENZODIAZOBOROLE.

3,677,945 STABILIZATION F LUBRICANTS Allen K. Sparks, Des Plaines, Ill.,assignor to Universal Products Company, Des Plaines, Ill.

No Drawing. Continuation-impart of application Ser. No. 843,852, July22, 1969, now Patent No. 3,629,190, which is a continuation-in-part ofapplication Ser. No. 623,805, Mar. 17, 1967, now Patent No. 3,481,978.This application Mar. 12, 1971, Ser. No. 123,820

Int. Cl. C10m 1/54 US. Cl. 252-49.6 6 Claims ABSTRACT OF THE DISCLOSUREStabilizing lubricants against deterioration during transportation,storage and/or use by incorporating therein a Zhydrocarbyl-l,3-di-sec-alkyl or di-cycloalkyl-2H-1,3,2-benzodiazoborole.

v CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation-of-partof copending application Ser. No. 843,852, filed July 22, 1969 and nowPatent 3,629,190, issued Dec. 21, 1971, which, in turn, is acontinuation-of-part of application Ser. No. 623,805, filed Mar. 17,1967, and now Pat. 3,481,978, issued Dec. 2, 1969.

DESCRIPTION This invention relates to the stabilization of lubricants byincorporating therein an additive comprising a particularly substitutedbenzodiazoborole.

The additive of the present invention is illustrated by the followingformula where R, and R are sec-alkyl or cycloalkyl, R" is hydrocarbyl,and Y is hydrogen, hydrocarbyl, hydrocarbyloxy, halogen or nitro.

It is an essential feature of the present invention that R and R are ofsecondary alkyl configuration or cycloalkyl. These compounds possessimproved potency as additives to organic substrates. The sec-alkylgroups may contain from 3 to 20 carbon atoms each and thus will beselected from isopropyl, sec-butyl, sec-pentyl, sec-hexyl, sec-heptyl,sec-octyl, sec-nonyl, sec-decyl, sec-undecyl, secdodecyl, sec-tridecyl,sec-tetradecyl, sec-pentadecyl, sechexadecyl, sec-heptadecyl,sec-octadecyl, sec-nonadecyl and sec-eicosyl. The cycloalkyl groups maycontain from 3 to 12 carbon atoms each and, in a particularly preferredembodiment, comprises cyclohexyl.

Referring to the above formula, R" is hydrocarbyl and will be selectedfrom alkyl, alkaryl, aryl, aralkyl or cycloalkyl. The alkyl moiety maybe of primary, secondary or tertiary configuration and willcontain from1 to 20 carbon atoms or more. Where R" is aryl, it will be selected fromphenyl, naphthyl, anthracyl, etc., and may contain alkyl substituentsattached to the aryl nucleus. Thus, the alkaryl groups may comprisetoluene, ethyl benzene, propyl benzene, etc., in which the alkyl moietycontains up to about 20 carbon atoms. Also the alkaryl substitution maycontain two alkyl groups attached to the aryl nucleus and thus mayinclude Xylene, diethyl benzene, dipropyl benzene, etc., in which eachalkyl group may. contain from 1 to 20 carbon atoms and may be the sameor of a different number of 3,577,945 Patented July 18, 1972 carbonatoms and/or of configuration. Where R" is aralkyl, illustrative groupsinclude benzyl, phenylpropyl, phenylbutyl, phenylpentyl, phenylhexyl,phenylheptyl, phenyloctyl, etc., which group also may contain one or twoalkyl substituents attached to the phenyl nucleus. Where R" iscycloalkyl, the alkyl group contains from 3 to 12 carbon atoms in thering and thus will be selected from cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl,cyclodecyl, cycloundecyl and cyclododecyl. Here again, cyclohexyl isparticularly preferred.

Where Y is hydrocarbyl, it may be selected from those hereinbeforespecifically set forth. Where Y is hydrocarbyloxy, it may comprisealkoxy or phenoxy, the latter also may contain alkyl substituentsattached to the phenyl nucleus. The hydrocarbyl moiety of thehydrocarbyloxy group will be selected from the hydrocarbyl groupshereinbefore specifically set forth. Where Y is halogen, it Will beselected from chlorine, bromine, fluorine or iodine, preferably beingchlorine or bromine.

Illustrative preferred compounds of the present invention include2-nonyl-l,3-di-sec-heXyl-2H-1,3,2-benzodiazoborole,Z-nonyl-1,3-di-sec-heptyl-2H-1,3,2-benzodiazoborole,2-nonyl-1,3-di-sec-octyl-2H-1,3,2-benzodiazoborole,2-nonyl-1,3-di-sec-nonyl-2H-1,3,2-benzodiazoborole,2-nonyl-1,3-di-sec-decyl-2H-1,3,2-benzodiazoborole,2-nonyl-1,3-di-sec-undecyl-2H-1,3,2-benzodiazobor0le, 2-nonyl-1,3-di-sec-do de cyl-2H- 1,3 ,2- benzodiazoborole,

etc., and corresponding compounds in which the 2-nonyl group is replacedby propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,nonadecyl, eicosyl, etc. As hereinbefore set forth, the R substitutionmay be of primary, secondary or tertiary alkyl configuration.

In another preferred embodiment, R is phenyl and illustrative compoundsinclude Z-phenyl-l,3-di-sec-heXyl-2H-1,3,2-benzodiazoborole, Z-phenyl-1,3-di-sec-heptyl-2H- 1,3,2-benzodiazoborole, 2-phenyl-1,3-di-sec-octyl-2H- 1, 3 ,2-benzodiazob orole,Z-phenyl-1,3-di-sec-nonyl-2H-1,3,2-benzodiaz0borole,Z-phenyl-1,3-di-sec-decyl-2H-1,3,2-benzodiazoborole,2-pheny1-1,3-di-sec-undecyl-2H-1,3,2-benzodiazoboro1e,Z-phenyl-1,3-di-sec-dodecyl-2H-1,3,2-benzodiazoborole,

etc. In another embodiment the phenyl group is replaced by naphthyl andillustrative compounds will correspond to those set forth above exceptthat the phenyl group will be replaced by naphthyl.

The compounds of the present invention are prepared in any suitablemanner. In a particularly preferred method, o-phenylenediamine issubjected to reductive alkylation with a ketone in the presence ofhydrogen to form N,N'- di-sec-al-kyl-o-phenylenediamine, which then isreacted with an alkyl or aryl boronic acid. In preparing theN,N'-di-sec-alkyl-o-phenylenediamine, the ketone used in the reductivealkylation will be selected to produce the desired sec-alkylderivatives. For example, the di-isopropyl derivaive is prepared usingacetone as the ketone, the di-sec-butyl derivative is prepared by usingmethyl ethyl ketone, the di-sec-pentyl derivative is prepared by usingmethyl propyl ketone or diethyl ketone, etc. The dicyclohexyl derivativeis prepared by using cyclohexanone as the ketone. The reductivealkylation is eifected in any suitable manner and, in a preferredmethod, the reaction is elfected in the presence of a reductivealkylation catalyst. The reductive alkylation catalyst includes thosecontaining nickel, molybdenum, platinum, palladium, etc. A preferredcatalyst comprises a composite of alumina and 0.5 to

10% by weight of platinum, which catalyst may or may not contain fromabout 0.1 to by weight of chlorine and/or fluorine. At least two moleproportions of ketone per mole proportion of o-phenylenediamine is usedand preferably an excess of ketone is employed in order to insure thatthe desired reductive alkylation is effected and this excess may rangeup to 40 mole proportions of ketone per 1 mole proportion ofo-phenylenediamine.

The N,N'-di-sec-alkyl-o phenylenediamine or dicycloalkyl derivativeprepared in the above manner is then reacted with alkyl or phenylboronic acid. The reaction preferably is effected in the presence of asolvent. Any suitable solvent may be employed and preferably is anaromatic solvent, including benzene, toluene, xylene, ethyl benzene,cumene, etc. The temperature of reaction will vary with the particularsolvent and may be within the range of from SO -300 C. The reaction iseffected by refluxing the mixture of reactants and solvent for asufltlcient time to effect completion of the reaction, which time may bewithin the range of from about 2 to 24 hours or more. The water formedduring the reaction preferably is continuously removed. Followingcompletion of the reaction, the novel compound of the present inventionmay be recovered in admixture with the solvent, or the solvent may beremoved by distillation, preferably under vacuum, or in any othersuitable manner.

The novel compound of the present invention generally will comprise aheavy liquid and may be used as such, but preferably will be used insolution in a suitable solvent which may include the solvent used in thereaction or it may be a different solvent. In any event the solvent willbe selected to be compatible with the organic substrate into which thenovel compound is to be incorporated. The solvent may be selected fromhydrocarbons and particularly aromatics, as hereinbefore set forth, orparafllm'c hydrocarbons including pentane, hexane, heptane, nonane,decane, etc., cycloparaflins and particularly cyclohexane, etc. Thecompounds of the present invention may be used in a concentration in thesolvent of from to 80% and preferably from 20 to 70% by weight thereof.

The compounds of the present invention are useful as additives to retarddeterioration of lubricants which normally tend to deteriorate instorage, transportation and/ or in use due to oxidation, ozonation,ultraviolet light absorption and/ or other reactions.

The compounds of the present invention are used in the stabilization oflubricants including lubricating oils and greases. These may be eithersynthetic or of petroleum origin. The synthetic lubricating oils are ofvaried types including aliphatic esters, polyalkylene oxides, silicones,esters of phosphoric and silicic acids, highly fluorinesubstitutedhydrocarbons, etc. Of the aliphatic esters, di- (Z-ethylhexyl) -sebacateis being used on a comparatively large commercial scale. Other aliphaticesters include dialkyl azelates, dialkyl suberates, dialkyl pimelates,dialkyl adipates, dialkyl glutarates, etc. Specific examples of theseesters include dihexyl azelate, di-(2ethylhexyl)-azelate,di-3,5,5-tri-methylhexyl glutarate, di-3,5,5-trimethylpentyl glutarate,di-(Z-ethylhexyl)-pimelate, di-(2-ethylhexyl)- adipate, tri-amyltricarballylate, pentaerythritol tetracaproate, pentaerythritoltetrapelargonate, dipropylene glycol dipelargonate,1,5-pentanediol-di-(Z-ethylhexanonate), etc. The polyalkylene oxidesinclude polyisopropylene oxide, polyisopropylene oxide diether,polyisopropylene oxide diester, etc. The silicones include methylsilicone, ethylphenyl silicone, etc. and the silicates include, forexample, tetraisooctyl silicate, etc. The highly fluorinatedhydrocarbons include fiuorinated oil, perfluorohydrocarbons, etc.

Additional synthetic lubricating oils include (1) neopentyl glycolesters, in which the ester group contains from 3 to 12 carbon atoms ormore, and particularly neopentyl glycol propionate, neopentyl glycolbutyrate,

neopentyl glycol caproate, neopentyl glycol caprylate, neopentyl glycolpelargonate, etc., (2) trialkylol alkane esters such as the esters oftrimethyol alkanes including tri methylol ethane, trimethylolpropane,trimethylolbutane, trimethylolpentane, trimethylolhexane,trimethylolheptane, trimethyloloctane, trimethylolnonane,trimethyloldacane, trimethylol, undecane, trimethyloldodecane, etc., andparticularly triesters in which the ester portions each contain from 3to 12 carbon atoms and may be selected from those hereinbeforespecifically set forth in connection with the discussion of theneopentyl glycol esters,

"and (3) tricresylphosphate, triphenylphosphate, trioctylphosphate,trinonylphosphate, tridecylphosphate, as well as mixed aryl and alkylphosphates, etc. I

The lubricating oils ofpetroleum origin include those referred to asmotor lubricating oil, railroad type lubricating oil, marine oil,transformer oil, turbine oil, transmission oil, differential oil, diesellubricating oil, gear oil, cutting oil, rolling oil, cylinder oil,hydraulic oil, slushing oil, specialty products oil, etc.

The synthetic greases generally are referred to as lithium base grease,sodium base grease, calcium base grease, barium base grease, strontiumbase grease, aluminum base grease, etc. These greases are solid orsemi-solid gels and, in general, are prepared b the addition to mineraland/ or synthetic oil of hydrocarbon-soluble metal soaps or salts ofhigher fatty acids as, for example, lithium stearate, calcium stearate,aluminum naphthenate, etc. The grease may contain thickening agents suchas silica, carbon black, polyacrylates, talc, etc. Another type ofgrease is prepared from oxidized petroleum wax, to which thesaponifiable base is combined with the proper amount of the desiredsaponifying agent, and the resultant mixture processed to produce agrease. Other types of greases in which the features of the presentinvention are usable include petroleum grease, whale grease, woolgrease, etc., and those made from inedible fats, tallow, butchers waste,etc.

The compounds of the present invention may be used in a concentration offrom about 0.001% to about 20% and more particularly from about 0.1% toabout 5% by weight of the lubricant. The exact concentration to be usedwill depend upon the particular lubricant being stabilized.

It is understood that the compound of the present invention may be usedalong with other additives incorporated in the organic substance. Forexample, in grease it may be used along with higher alcohols, esters,organic amines, polybutene, sulfurized fatty materials, sulfur chlorinecompounds molybdenum disulfide, dyes, perfumed materials, fillers, etc.In lubricating oil, it may be used along with one or more of the aboveadditives and/or viscosity index improver, pourpoint depressor,anti-foaming agent, detergent, lubricity or extreme pressure addr tive,etc. In some cases, it may be of advantage to also include a metaldeactivator as, for example disalicylal diaminopropane, ethylene diaminetetraacetic acid tetrasodium salt, etc., or to include other additivessuch as tricresyl phosphate, trialkyl phenols including 2,6-di-tertbutyl4 methylphenol, 2,4-dimethyl-6-tert-butylphenol, alkylated diphenylamines, phenyl naphthyl 011111105, d1- alkyl phenylenediamines,phenothiazine, organrc selenium compounds, etc. When desired, thecompound of the present invention may be prepared as a mixture with oneor more of these other additives and incorporated in this manner in thelubricant.

The compound of the present invention may be incorporated in thelubricant in any suitable manner and at any suitable stage ofpreparation. For example, in grease, the compound may be added to one ormore of the components of the grease prior to compositing and processingthereof, or it may be added to the mix at any time, preferably beforefinal processing in order to obtain intimate mixing and dissolving ofthe compound in the grease. When added to lubricating oil, the compoundis incorporated in any suitable manner and preferably with mixing toobtain uniform distribution in the oil.

EXAMPLE I The compound of this example is2-nonyl-1,3-di-secoctyl-ZH-1,3,2-benzodiazoborole and was prepared byreacting nonyl boronic acid with N,N-di-sec-octyl-o-phenylenediamine,the latter being prepared by reductive alkylation of o-phenylenediaminewith octyl ketone at about 160 C., 100 atmospheres of hydrogen and incontact with an alumina-platinum catalyst. The reaction was effected byrefluxing a mixture of 37 g. of N,N'-di-secoctyl-o-phenylenediamine, 23g. of nonyl boronic acid and 250 cc. of benzene. The refluxing wascontinued for 6 hours, and 2.5 cc. of water was recovered from thedistillation. Following completion of the reaction, 56 g. of2-nonyl-1,3-di-sec-octyl-2H-1,3,2 benzodiazoborole was recovered as areddish liquid. This corresponds to the theoretical yield of 56.9 g.Analysis of the product found a. boron content of 2.35% by weight andbasic nitrogen of 1.97 meq./ g. which equals a molecular weight of 507.6and corresponds to the theoretical molecular weight of 513.5.

EXAMPLE II The compound of this example is2-phenyl-1,3-di-secbutyl-ZH-l,3,2-benzodiazoborole and is prepared byfirst subjecting o-phenylenediamine to reductive alkylation with methylethyl ketone and then reacting 1 mole proportion of theN,N'-di-sec-butyl-o-phenylenediamine with phenyl boronic acid. Thelatter reaction is efiected by refluxing the reactants in the presenceof benzene solvent and removing the water formed in the reaction. Aftercompletion of the reaction 2-phenyl-1,3-di-sec-butyl-2H-1,3,2-benzodiazoborole is recovered in admixture with the benzenesolvent and is utilized in this manner as an additive to organicsubstrates.

EXAMPLEIH The compound of this example is2-cyclohexyl-1,3-disec-hexyl-ZH-1,3,2-benzodiazoborole and is preparedby first subjecting o-phenylenediamine to reductive alkylation withethyl propyl ketone to form N,N'-di-sec-hexyl-ophenylene diamine andthen reacting the same with cyclohexyl boronic acid in the presence oftoluene solvent under refluxing conditions for 8 hours. The2-cyclohexy1-1,3-disec-hexyl-2H-l,3,2-benzodiazoborole is recoveredinadmixture with the toluene solvent and is utilized in this manner.

EXAMPLE IV The compound of this example is2-decyl-l,3-di-cyclohexyl-ZH-1,3,2-benzodiazoborole and is prepared byfirst reductively alkylating o-phenylenediamine with cyclohexanone toform N,N-di-cyclohexyl-o-phenylenediamine and then reacting the samewith decyl boronic acid in the presence of benzene solvent underrefluxing conditions for 7 hours. The resultantZ-decyl-1,3-di-cyclohexyl-2I-I- 1,3,2-benzodiazoborole is recovered inadmixture with the benzene solvent and is used in this manner as anadditive.

EXAMPLE V The compound of this example is2-naphthyl-1,3-diisopropyl-ZH-1,3,2-diazoborole and is prepared by firstsubjecting o-phenylenediamine to reductive alkylation with acetone andthen reacting one mole proportion of theN,N-diisopropyl-o-phenylenediamine with naphthyl boronic acid. The laterreaction is effected by refluxing the reactants in the presence ofxylene solvent and removing the 'water formed during the reaction. Aftercompletion of the reaction, Z-naphthyl-1,3-di-isopropyl-2H-1,3,2-benzodiazoborole is recovered in admixture with xylene solvent andis utilized in this manner as an additive to organic substrates.

6 EXAMPLE v1 The compound of this example is2-cyclooctyl-1,3-distearyl-ZH-1,3,2-benzodiazoborole and is prepared insubstantially the same manner as described above by first subjectingo-phenylenediamine to reductive alkylation with ethylpentadecyl ketoneand then reacting the same with cyclooctyl boronic acid in the presenceof xylene solvent. TheZ-cyclooctyl-l,3-di-stearyl-2H-1,3,2-benzodiazoborole is recovered inadmixture with the solvent.

EXAMPLE VII This example illustrates the use of2-nonyl-1,3-di-secoctyl-2H-1,3,2-benzodiazoborole, prepared as describedin Example I, as an additive in lubricating oil. The lubricating oilused in this example is a synthetic lubricating oil marketed under thetrade name of Plexol 201 and is dioctyl sebacate.

The lubricating oil was evaluated inaccordance with a standard oxygenstability test in which a cc. sample of the lubricating oil is placed ina batch maintained at 204 C, and air is blown therethrough at a rate of5 liters of air per hour. The test is continued for 48 hours. Thekinematic viscosities at the start of the test, after 24 hours and after48 hours were determined. In addition, the percent of isooctaneinsoluble materials was determined.

The following table reports the results of an evaluation of the controlsample of the lubricating oil (not containing the additive) and a sampleof the lubricating oil containing 2% by weight of2-nonyl-1,3-di-sec-octyl-2H- 1,3,2-benzodi-azoborole.

From the data in the above table it will be seen that the control sampleof the lubricating oil (without additive) underwent an increase ofapproximately 100% in kinematic viscosity. In contrast, the samplecontaining the additive underwent an increase of less than 10% inkinematic viscosity.

In the control sample, the percent of material insoluble in iso-octanewas 8.2%. In contrast the percent of iso-octane insolubles in the samplecontaining the additive was 0.1%. This again demonstrates theeffectiveness of the compound of the present invention to retarddeleterious reactions in the lubricating oil during evaluation in theabove manner.

EXAMPLE VIII In this example 2-cyclohexyl-1,3-di-sec-hexyl-2H-1,3,2-benzodiazoborole, prepared as described in Example III, is utilized in aconcentration of 1% by weight as an additive in grease. The compound isincorporated in a commercial Mid-Continent lubricating oil having an SAEviscosity of 20. Approximately 92% of the lubricating oil then is mixedwith approximately 8% by weight of lithium stearate. The mixture isheated to about 232 C., with constant agitation. Subsequently, thegrease is cooled, while agitating, to approximately C., and then thegrease is further cooled slowly to room temperature.

The stability of the grease is tested in accordance with ASTM D-942method, in which method a sample of the grease is placed in a bomb andmaintained at a temperature of 100 C. Oxygen is charged to the bomb, andthe time required for a drop of five pounds pressure is taken as theInduction Period. A sample of the grease without additive will reach theInduction Period in about eight hours. On the other hand, a sample ofthe grease containing 1% by weight of the additive of the presentinvention will be of substantially higher stability.

7 EXAMPLE IX In this example, Z-decyl-1,3-di-cyclohexyl-2H-1,3,2-benzodiazoborole, prepared as described in Example IV, is used as anadditive in commercial motor lubricating oil of petroleum origin. Theadditive is incorporated in a concentration of 3% by weight and servesto retard deterioration of the lubricating oil during storage and use.

I claim as my invention:

1. Lubricant selected from the group consisting of lubricating oils andgreases normally tending to undergo deterioration during transportation,storage or use con taining, as an inhibitor against such deterioration,a stabilizing concentration of '2-hydrocarbyl-1,3-di-C -C-secalkyl-ZH-1,3,2-benzodiazoborole or 2-hydrocarbyl-l,3-di- C -C-cycloalky1-2H-1,3,2-benzodiazoberole,

2. The lubricant of claim 1 being lubricating oil.

3. The lubricant of claim 1 being a solid lubricant.

8 4. The lubricant of claim 1 wherein the inhibitor is2-nony1-1,3-di-sec-octyl-2H-1,3,2-benzodiazoborole.

5. The lubricant of claim 1 wherein the inhibitor is 2-cyclohexyl-1,3-di-sec-hexy1-2H-l,3,2-benzodiazoborole.

6. The lubricant of claim 1 wherein the inhibitor is 2- decyl- 1, 3-di-cycl0l1eXyl-2H- 1, 3,2-benzodiazoboro1e.

References Cited.

UNITED STATES PATENTS 3,213,136 10/1965 Washburnetal. 252-496 X3,338,962 8/1967 Horn 252 49.6 X

DANIEL E. WYMAN, Primary Examiner 15 W. H. CANNON, Assistant ExaminerUS. Cl. X.R. 252-400

